Drill bit cutter with stress reducing features

Abstract

A variety of methods, systems, and apparatus are disclosed, including, in one embodiment, a drill bit, comprising: a bit body defining a rotational axis and having a plurality of cutter pockets formed thereon, each cutter pocket shaped to receive a respective substrate of a cutter with a cutting table secured thereon, wherein the substrate of at least one cutter has an outer profile defining an area of increased braze gap; and a braze interface comprising a braze alloy disposed in each cutter pocket between the inner profile of the cutter pocket and the outer profile of the respective substrate, such that a thickness of the braze alloy is greater at the area of increased braze gap.

What is claimed is: 
     
       1. A drill bit, comprising:
 a bit body defining a rotational axis and having a plurality of cutter pockets formed thereon, each cutter pocket shaped to receive a respective substrate of a cutter with a cutting table secured thereon, wherein the substrate of at least one cutter has an outer profile defining an area of increased braze gap, wherein the area of increased braze gap is along an annular gap defined between the cutter pocket and the substrate, wherein the cutter has a central cutter axis and a cutter length in an axial direction, and the area of increased braze gap has an axial length of between 5% and 90% of the overall cutter length, and wherein the area of increased braze gap extends axially along the substrate and is no more than 20% of the overall cutter length away from the front of the cutting table; and 
 a braze interface comprising a braze alloy disposed in each cutter pocket between the inner profile of the cutter pocket and the outer profile of the respective substrate, such that a thickness of the braze alloy is greater at the area of increased braze gap. 
 
     
     
       2. The drill bit of  claim 1 , further comprising a uniform gap between the inner and outer profiles outside the area of increased braze gap. 
     
     
       3. The drill bit of  claim 1 , wherein the area of increased braze gap extends axially along the substrate and terminates below the cutting table. 
     
     
       4. The drill bit of  claim 1 , wherein the area of increased braze gap extends through at least a portion of the cutting table. 
     
     
       5. The drill bit of  claim 1 , wherein the area of increased braze gap has a circumferential width of less than half of a perimeter of the substrate. 
     
     
       6. The drill bit of  claim 1 , wherein the area of increased braze gap comprises an annular groove, which extends a full 360 degrees along the annular gap. 
     
     
       7. The drill bit of  claim 6 , wherein the area of increased braze gap has a lateral width of between 5% and 90% of a width of the substrate. 
     
     
       8. The drill bit of  claim 1 , wherein the area of increased braze gap comprises a plurality of circumferentially spaced recess portions along an annular gap defined between the cutter pocket and the substrate. 
     
     
       9. The drill bit of  claim 1 , wherein a depth of the area of increased braze gap and the corresponding thickness of the braze alloy at the area of increased braze gap are between 0.010 inches and 0.030 inches. 
     
     
       10. The drill bit of  claim 1 , wherein the braze interface includes a region of compression and a region of tension under a drilling loading, and wherein the area of increased braze gap is positioned in the cutter pocket within the region of tension. 
     
     
       11. The drill bit of  claim 1 , wherein the braze alloy comprises at least one alloy selected from the group consisting of a copper-based alloy, a nickel-based alloy, a silver-based alloy, a gold-based alloys, and combinations thereof. 
     
     
       12. A braze joint, comprising:
 a cutter substrate having an outer profile; 
 a cutter pocket for receiving the cutter substrate and having an inner profile with a uniform gap between the inner and outer profiles outside an area of increased braze gap defined along the outer profile of the substrate, wherein the area of increased braze gap is along an annular gap defined between the cutter pocket and the substrate, and wherein the area of increased braze gap extends axially along the substrate and is no more than 20% of the overall cutter length away from the front of a cutting table secured to the cutter substrate; and 
 a braze interface comprising a braze alloy disposed in the cutter pocket between the inner profile of the cutter pocket and the outer profile of the respective substrate, such that a thickness of the braze alloy is greater at the area of increased braze gap. 
 
     
     
       13. The braze joint of  claim 12 , wherein the cutter has a central cutter axis and a cutter length in an axial direction, and the area of increased braze gap has an axial length of between 5% and 90% of the cutter length, and wherein the area of increased braze gap extends through at least a portion of the cutting table. 
     
     
       14. The braze joint of  claim 12 , wherein the area of increased braze gap has a circumferential width of less than half of a perimeter of the substrate. 
     
     
       15. The braze joint of  claim 12 , wherein the area of increased braze gap extends a full 360 degrees along the annular gap.